OutsSelf, I may be misunderstanding you, but you seem to be arguing that pregnancy socially disadvantages people because it is associated with the sex class women, and only because of that.
And then you are saying, there was no such thing as women (in social understanding), then we would then just have the idea that anyone can become pregnant and no system of discrimination would exist.
You are then saying that perceiving females as people who may become pregnant is unfair on the females who either don't want to become pregnant or can't.
If that is not what you are saying, then I'm sorry for misunderstanding you.
I don't think any of that would work for the reason I have already given of having to make a distinction between people to see who is experiencing the discrimination. Not all discrimination is deliberate. It can come into being by simply not recognising that a group exists and that it has different needs.
If we were to decide what kind of society would best meet the needs of people who can get pregnant, then the people best able to answer that question are the people it actually happens to, and they will be explain it through a series of life events before, during or after pregnancy.
And one of the major elements of that would be recognising that there a different group of people who have the capacity to impregnate without medical intervention, and those people carry a specific risk of being able to impregnate people, and females should have a right to know who is likely to carry that risk. It is not helpful to make out that any person may impregnate somebody and we should all walk around behaving as if all contact with all people carries that risk and should act accordingly. It is a basic thing people need to know - sex education. To try and set up a system at a higher level where we don't recognise this, when on a lower interpersonal level everyone will still have to recognise this to make reproductive choices is unworkable.
As for the unfairness to females who don't get pregnant, I said this was the crux of the whole issue on one of the first transgenderism threads.
For the first time in history, we have a situation where large numbers of women (mostly white, well educated, relatively wealthy and living in MEDCs) have chosen not to become pregnant, or to delay pregnancy until their thirties. Many of these women are now arguing that women being a reproductive class should not be the focus of feminism.
Which makes sense for them, because they are not part of the reproductive class to the extent that most other women are, and to defend their own interests (I shouldn't be lumped in with these breeders etc) they can make themselves the women who are most oppressed, or at least marginalise mothers.
While at the same time, African American women are three times more likely to die as a consequence of childbirth than white American women, and taking Africa as a whole (which is how the stats put it, rather than how I'd like to break it down) one in sixteen of all women in Africa will die as a direct consequence of childbirth or pregnancy. And many females globally become pregnant before they even become women (an adult human female).
So the whole idea that we should make the unfairness of talking about women as if it is not mainly about people who may become pregnant is hugely ideological within the context we are in. And I don't see a point in talking about gender and sex in any other context than the one we live in, and being aware of who stands to benefit from arguing for one supposedly neutral set of statements over another.